Non-destructive laser heating has a variety of applications in the field of medicine, including the alteration of tissue stress and structure for cartilage reshaping in otolaryngology and for the activation of reparative processes in joints and spine discs in orthopedics and spine surgery. Existing approaches suffer from significant limitations as a result of overheating of the tissue joining the ablation zone and the undesirable effect on surrounding tissues, which manifest as scarring and/or increased probability of relapse.
The limitations of the existing technologies are associated with difficulties in controlling the modification processes of the tissue structure and the mechanical properties of the tissue. For example, one particularly difficult aspect for nasal septum reshaping is the selection of the optimal treatment site. The area of laser application should ideally be determined according to the initial septum shape and the distribution of initial stress in the tissue, however, these properties vary widely among patients and across a given tissue area. Using existing methods, laser radiation is applied along a bent line, which diminishes efficacy and limits the number of septum deviation types that can be corrected.
Similar issues arise for laser regeneration of disks (LRD). Since the optical properties of the tissue are also individual and depend on the tissue age and condition, in particular the water content, the initial choice of the laser settings and any adjustments to be made to the laser settings in the course of LRD are not systematically selectable using existing methods. In this case, the safety of the laser treatment is defined by the breadth of the therapeutic window, and the initial laser settings are chosen near the lower boundary of the therapeutic window (i.e., in the range of safe laser settings). Thus, there is only a narrow range of laser conditions that are both efficacious and non-destructive to tissues, and existing methods fail to provide adequate guidance regarding the selection of initial laser settings.
During laser irradiation of tissue, the treated area undergoes a number of changes, including without limitation: changes in temperature, porosity, absorptivity, residual stress across an area of tissue, and the like. While methods exist for independently measuring changes in certain individual properties, no known method exists that is capable of comprehensively measuring these characteristics and integrating them for use in a feedback system. Moreover, no known method exists that enables the use of these measurements as feedback to improve the efficacy and safety of the laser treatment of tissue. Existing methods are incapable of providing guidance regarding initial laser settings, including optimized selection of the treatment site. Existing methods also fail to provide real-time measurement of a combination of tissue condition parameters that enable the customization of treatment conditions for improved efficacy and safety.
Therefore, a need exists in the art for improved methods and tools that are responsive to a number of parameters as measured during the course of laser tissue treatment and are capable of taking into account a variety of factors affecting the efficacy and safety of non-destructive laser heating treatments.